Base station and communication method

Abstract

A base station relates to a wireless communication system that performs handover from a cell connected with a terminal to a neighbor cell of the cell. The base station includes: circuitry, which, in operation, sets an offset to be applied to reception quality of the neighbor cell according to a quality of service (QoS) class identifier (QCI) of the terminal when the terminal determines whether to report a measurement result to be used in determination on the handover; and a transmitter, which, in operation, transmits the offset to the terminal.

The invention claimed is: 
     
       1. A base station in a wireless communication system that performs handover from a cell connected with a terminal to a neighbor cell of the cell, the base station comprising:
 circuitry, which, in operation, sets an offset to be applied to reception quality of the neighbor cell when the terminal determines whether to report a measurement result to be used in determination of the handover, 
 wherein the circuitry, in operation, sets a variable offset according to a quality of service (QoS) class identifier (QCI) of the terminal, and adds the variable offset to a reference offset to obtain the offset to be applied to the reception quality of the neighbor cell, 
 wherein the circuitry, in operation, sets the variable offset to a value less than or equal to zero to in response to determining that an allowable delay time or an allowable packet loss corresponding to the QCI of the terminal is less than or equal to a threshold, and 
 wherein the circuitry, in operation, sets the variable offset to a value greater than zero in response to determining that the allowable delay time or the allowable packet loss corresponding to the QCI of the terminal is greater than the threshold; and 
 a transmitter, which, in operation, transmits information indicating the offset to be applied to the reception quality of the neighbor cell to the terminal. 
 
     
     
       2. The base station according to  claim 1 , wherein, in response to determining that the allowable delay time corresponding to the QCI of the terminal is larger than the threshold, the circuitry increases the offset to be applied to the reception quality of the neighbor cell. 
     
     
       3. The base station according to  claim 1 , wherein, in response to determining that the allowable packet loss corresponding to the QCI of the terminal is larger than the threshold, the circuitry increases the offset to be applied to the reception quality of the neighbor cell. 
     
     
       4. The base station according to  claim 1 , wherein, when radio link failure occurs in the terminal after the terminal is handed over from the cell of the base station to the neighbor cell, the circuitry reduces the offset to be applied to the reception quality of the neighbor cell for the terminal. 
     
     
       5. The base station according to  claim 1 , wherein the transmitter transmits information on setting of the offset to be applied to the reception quality of the neighbor cell to another base station of the neighbor cell. 
     
     
       6. The base station according to  claim 1 , further comprising a receiver, which, in operation, receives information on setting of the offset to be applied to the reception quality of the neighbor cell in the neighbor cell from another base station of the neighbor cell, wherein
 the circuitry sets the offset to be applied to the reception quality of the neighbor cell for determination on the handover from the cell of the base station to the neighbor cell based on the information on setting of the offset to be applied to the reception quality of the neighbor cell in the neighbor cell. 
 
     
     
       7. The base station according to  claim 1 , wherein, when the offset to be applied to the reception quality of the neighbor cell for the terminal is set higher than a reference value, the circuitry retains information on the terminal for a certain period of time without deleting the information on the terminal, when the terminal is handed over to the neighbor cell. 
     
     
       8. A communication method in a wireless communication system that performs handover from a cell connected with a terminal to a neighbor cell of the cell, the communication method comprising:
 setting an offset to be applied to reception quality of the neighbor cell when the terminal determines whether to report a measurement result to be used in determination of the handover, 
 wherein the setting the offset to be applied to the reception quality of the neighbor cell includes:
 setting a variable offset according to a quality of service (QoS) class identifier (QCI) of the terminal, wherein the setting the variable offset includes setting the variable offset to a value less than or equal to zero in response to determining that an allowable delay time or an allowable packet loss corresponding to the QCI of the terminal is less than or equal to a threshold, and wherein the setting the variable offset includes setting the variable offset to a value greater than zero in response to determining that the allowable delay time or the allowable packet loss corresponding to the QCI of the terminal is greater than the threshold, and 
 adding the variable offset to a reference offset to obtain the offset to be applied to reception quality of the neighbor cell; and 
 transmitting information indicating the offset to be applied to the reception quality of the neighbor cell to the terminal. 
 
 
     
     
       9. The communication method according to  claim 8 , wherein the reference offset is commonly set for a plurality of terminals in the neighbor cell. 
     
     
       10. The base station according to  claim 1 , wherein the reference offset is commonly set for a plurality of terminals in the neighbor cell.